Simulink tools are not shown at the top of the window

Once in a while (i.e., I can't reliably recreate the problem) when resizing the Simulink window the menus/tools graphics will be blacked out. The buttons are still active since i can click within the black strip and get a response, but I can not see what I am selecting. Closing Simulink and reopening the model does not fix the problem, only by closing and reopening Matlab will the graphics be reset.

(since I couldn't reliably recreate the problem I made this image to show what the problem looks like)